Nonsticky flame-proofed electrical conduit, etc.



Patented May 31, r 1932 v UNITED STATES PATENT? OFFICE JOSEPH A. KENNEDY, OF PAWTUCKET, RHODE ISLAND, ASSIGNOR, IBY MESNE ASSIGN- MENTS, TO ANACONDA WIRE AND CABLE COMPANY, A CORPORATION OF DELA WARE NONSTICKY FLAME-PROCEED ELECTRICAL CONDUI'I, ETC.

No Drawing.

ductors, as it has suffici'ent flame-proofing properties to afford substantial protection against ignition of the conduit or insulation, respectively, by flame, and its use affords the fire protection required by the regulations of the National Board of Fire Underwriters.

However, this material, which is readily softened by heat, is very sticky when soft. It is applied to the goods in a heated fluid condition and remains sticky until thoroughly cooled to a temperature approximating the ordinary comfortable atmospheric temperatures. But when afterwards heated, whether by being exposed to the direct rays-of the sun on a hot day, or by being subjected to v 25 the temperature of a highly heated room, it

becomes sticky again.

Various means have been devised for neutralizing the sticky quality of the stearin pitch coating on such articles, including the 30 application of dry flakes of mica or other finely divided solid mineral applied while the coating is still warm and plastic, the apphcation of an outer film of wax, etc. But while these means are effective to some extent they are not entirely so; for the flaked or powdered mineral falls off more or less when the goods are handled, and the coating of wax melts and runs off when subjected to moderately high temperatures, leaving the stearin pitch surface more or less exposed and ob ectionably sticky. The heat imparted to the goods by exposure to the direct rays ofthe sun on a warm sunny day is sufficient to have 1 this effect in thecase of paraflin coated products. When thus deprived of the protective wax coating, the contacting parts of the conduit or cable, when coiled or otherwise arranged so that different partsof the article Application filed October 27, 1928. Serial No. 315,596.

off when these parts are afterwards separat ed. Also the sticky coating substance soils the hands and clothing of the workmen handling it, and anything else coming in contact with it.

According to the present invention I have devised a new mode of encasing the sticky surface coating on articles of the character hereinbefore indicated, which is free .from the defects above mentioned. I employ as an outer coating material, enveloping and encasing the sticky substance, a material which may be brought into the liquid state and applied in such state, and then, drying or hard ening, remains unaffected by any degree of heat to which the goods are liable to be subj ected in storage, shipment or in course of installation. I have found that a highly satisfactory substance for thus covering the sticky material is silicate of soda in water solution. However, I may use other materials with good effect, such as shellac or varnish dissolved in a volatile solvent, paint mixed with an oxidizable oil or other drying vehicle, etc. Generically, the invention comprises the combination with an article, such as electrical conduit, electrical cable or the like coated with a sticky compound, of an added coating of non-sticky material which is liquefiable and adherent to the previous coating material, becomes solid and dry when exposed to the air, and will not become sticky when subjected to heat alone, at least to heat within the ranges of temperature to which the mate- .rial may ever be subjected in the course of normal handling. As so vdefined, the invention is not necessarily limited to use with the particular goods before -mentioned, nor to goods coated onlywith stearin pitch rather than any other useful material which has an objectionable inherent stickiness, nor to any of the specific materials herein named as a suitable encasing substance. Nevertheless I claim as my invention and desire to protect herein, specifically as well as generically, the particular articles, materials and substances, and their combinations, described herein.

I will now briefly describe for illustration one particular mode of putting the invention touch one another, stick together, causing into eflect with the use of silicate of soda as so the pitch coating to be more or less stripped the outer coating material. The article to be covered, which for illustration may be assumed to be a seamless woven tube made of fibrous strands (cotton, twisted paper or- ,asphaltum, and then made flame-proof,

within the meaning of the term flame proof as used in the art, by being passed through a bath containing melted stearin pitch maintained in liquid condition by application of heat. I have found it satisfactory, and preferable, to follow this old practice and to apply the treatment in which my present invention consists to the goods as thus coated. Accordingly the pitch coated product is passed through a bath composed of silicate of soda in solution with water. Satisfactory proportions to use for this solution are two parts silicate of soda to three parts water. This bath is unheated except as it incidentally absorbs heat from the stearin pitch coating on the goods. It cools the goods and leaves a film on the surface which dries and encases the coating of stearin pitch.

The step involved in thus applying sili-- cate of soda adds no complication to the entire process of finishing the goods, for the usual commercial practice of making flex1 ble electrical conduit includes cooling it with water after leaving the bath of hot stearin pitch.

When other materials are used for the nonsticky top coating, they may be applied In the same way, or by any other suitable means which may be more appropriate to the character of the specific material used.

When thus coated with any of the materials suitable for the purpose, the finished product is non-sticky on the surface and remains so even when afterwards heated to comparatively higl temperatures. The turns of the coiled up product are thus prevented from adhering together, and the hands and clothing of workmen are protected from being soiled by the flame-proofing material when the product is being installed, even though the temperature should be high enough to destroy the utility of a wax film.

What I claim and desire to secure by Letters Patent is 1. A flexible insulated electrical conduit, insulated electrical conductor, or the like, enveloped by a non-bituminous coating of material which becomes fluid and sticky with heat, and an outer enveloping coating of dry non-sticky material having the property of remaining in that condition when the conduit or conductor is heated to a temperature suflicient to render the first named coating fluid and sticky.

2. A flexible insulated electrical conduit, insulated electrical conductor, or the like, enveloped by a coating of stearin pitch and an outer protective film of material having the property of remaining solid and nonsticky when the article has been heated to a temperture high enough to soften the stearin pitch coating.

-3. A flexible electrical conduit, insulated electrical conductor, or the like, having a coating of flame-proofing material which is softened and rendered sticky by heat, and a substantially solid outer coating of material covering the first named material and having the property of remaining substantially solid and non-sticky when the article is heated to a temperature high enough to soften the first named coating.

4. A flexible electrical conduit, insulated conductor, or the like, having a flameproofing coat of stearin pitch and an outer coat of substantially solid material which is non-sticky and has the property of remaining so when the article is heated to a temperature high enough to soften stearin pitch.

5. A flexible electrical conduit, insulated electrical conductor, or the like, having a coating of stearin pitch and an outer coating of dried silicate of soda.

6. The method of finishing flame-proofed electrical conduit, insulated electrical cable, and the like. which comprises passing the article, after having been coated with flameproofing material, through a liquid vehicle containing a substance which becomes substantially solid upon drying of said vehicle and remains so when heated to a temperature suflicient to soften the flame-proofing compound, and then drying the film of said material. so deposited on the article.

7 The method of rendering permanently non-stickv a flexible electrical conduit, electrical cable. or the like, which has been coated with a flame-proofing compound, which comprises depositing on the flame-proofing coat a film of material in liquid suspension which has the property of becoming substantially solid and non-sticky upon drying and of remaining so when heated to the temperature at which the flame-proofing compound becomes sticky. and drying said film.

8. The method of finishing and rendering non-sticky flame-proofed electrical conduit, insulated electrical conductors, and the like, which Consists in passing the conduit or the like from a bath containing heated and liquetied. flame-proofing compound into a bath containing a cool solution of a material which. on drying, becomes substantially solid and non-sticky and has the property of remaining so when heated to a temperature high enough to make the flameproofing compound soft and sticky, and then drying the film of the material which re- Ail) mains on the conduit after its emergence from the last named bath.

9. The method of flame-proofing flexible electrical conduit and similar material, and neutralizing the stickiness of the flame-proofing compound, which consists in assing the conduit through a bath of hot me ted stearin pitch and then passing it through a bath of a cool liquid solution of material which, on drying, is solid and non-sticky and remains so at a temperature high enough to soften stearin pitch.

. 10. The method of finishing flexible electrical conduit, insulated electrical conductors and similar manufacturers, which consists in passing the manufactured article through a bath of hot melted stearin pitch to give it flame-resisting qualities, andthen passing it through a relatively cool solution of silicate of soda, and drying the film of solution so-deposited on the goods.

In testimony whereof I have aflixed my signature. v

JOSEPH A. KENNEDY. 

